Overbased detergents are well described to provide lubricating properties. Often such detergent additives are proportioned with other lubricating additives to provide lubricating oil compositions that exhibit certain desired lubricating properties. Overbased alkaline metal or alkaline-earth metal sulfonates are examples.
European Patent Application Publication No. 1,059,301A1 describes alkaline-earth metal aralkylsulfonates having improved detergent and dispersant properties.
International Application WO 97/46644 describes a calcium overbased detergent comprising a surfactant system derived from at least two surfactants, in which at least one of the surfactants is a sulfurised or non-sulfurised phenol, or at least one other of the surfactants is other than a phenol, for example a sulfonic acid derivative, the proportion of phenol in the surfactant system being at least 35% by mass, and the TBN/% surfactant ratio of said detergent being at least 15.
International Application WO 97/46645 describes a calcium overbased detergent comprising a surfactant system derived from at least two surfactants in which at least one of the surfactants is a sulfurised or non-sulfurised phenol, or at least one other of the surfactants is a sulfurised or non-sulfurised salicylic acid, the total proportion of said phenol and of said salicylic acid in the surfactant system being at least 55% by mass, and the TBN/% surfactant ratio of said detergent being at least 11.
International Application WO 97/46647 describes a calcium overbased detergent comprising a surfactant system derived from at least two surfactants in which at least one of the surfactants is a sulfurised or non-sulfurised phenol, or at least one other of the surfactants is other than a phenol, for example an alkylarylsulfonate, the proportion of phenol in the surfactant system being at least 15% by mass, and the TBN/% surfactant ratio of said detergent being at least 21.
International Application WO 99/28422 describes a lubricating oil composition comprising a mixture of at least two detergents containing metals, namely, a) a phenate, sulfonate, salicylate, naphthenate or metal carboxylate, and b) an overbased calcium detergent comprising a surfactant system derived from at least two surfactants in which at least one of the surfactants is a sulfurised or non-sulfurised phenol, or at least one other surfactant is other than a phenol, the proportion of phenol in the surfactant system being at least 45% by mass, and the TBN/% surfactant ratio of said detergent being at least 14.